1. Field of the Invention
The present invention relates to a solid state electrode for the determination of sodium ion concentrations in solutions.
2. Technology Review
Glass membrane electrodes to measure sodium ion concentration are known, but these are expensive to manufacture. They are also fragile and sensitive to breaking and have a disadvantageously high cross sensitivity, for example for H.sup.+, Li.sup.+ and K.sup.+. In addition, glass membrane electrodes become somewhat sensitive to the alkali metals at pH values greater than 10. Thus, in a solution that is 1.0F in sodium ion, a negative error of nearly 1 pH unit is obtained at a pH of 12. Moreover, the glass membrane electrodes have a relatively high membrane resistance, up to about 500 megaohms. The measuring technology as a whole is complicated and sensitive to interference.